


I Never Knew

by Jadeandlogan



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell, Big Brother Papyrus, Dom Papyrus, Dom/sub, Flustered Sans, Fontcest, Incest, M/M, Sad Sans, Sibling Incest, Sub Sans
Language: English
Status: Completed
Published: 2015-12-15
Updated: 2015-12-17
Packaged: 2018-05-06 22:34:00
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence, No Archive Warnings Apply
Chapters: 3
Words: 4,292
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5433275
Author URL: https://archiveofourown.org/users/Jadeandlogan/pseuds/Jadeandlogan
Summary: <blockquote class="userstuff">
              <p>Sans tries to hide his desire for love and affection he had been trying to evoke from his brother, Papyrus. But he knew that it would never happen. So he suffered in silence, until Papyrus decided to take things seriously in his own hands,</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> dont like incest. dont read. its simple :>

"What?!" Papyrus slammed his fists down on the arm rest of his throne chair, "You are telling me that Sans destroyed all of these?!"

"Y-yes my lord", the servant bowed his head meekly. He was trembling in his shoes though he tried his best to maintain his composure. He was still holding the device that replays the video of Sans destroying the constructing buildings that were meant to be finished tomorrow.

Papyrus growled. Curse this wretched little brother of his!

 "You're dismissed", he grumbled, standing up from his throne as he made his way to his doors. Papyrus tightened balled his fists tighter, his red aura flowed aggressively around his figure.

It's time to teach his brother a lesson.  _ **Again.**_

~~~~~

Sans was walking down the judgement hallway. He destroyed another building. But it wasn't his  _intention._  All the destruction he caused, he did not meant it. It was all due to his anger and frustration of not having to get any praises or reward for the hard work he does. He always attempts to please his big brother, Papyrus, and hopefully evoke some at least affection. But he knew far too long that won't happen. It would never will. So what was the point of his efforts? What keeps him doing this? Hope? Faith?

He lost those along with the past. Everything changed. His brother became cold hearted. He himself became anxious, clumsy, and a desperate little shit. 

"Sans!" Papyrus exclaimed at the other end of the hallway, snapping Sans out of his thoughts. He straightened himself and forced a smile.

"h-hey b-brother", Sans piped up. 

"Do not 'hey' me!" Papyrus barked, grabbing Sans by the hoodie and pulled him close, "I had been receiving complaints that you had been causing inconvenience among the construction workers!" 

Sans shrunk back a bit, his voice faltered, "p-pap i-i can explain-"

"I do not want to hear your fucking excuses!" Papyrus knocked him onto the floor, "You are nothing but a troublesome person! I wish you were out of my life!"

Those words struck Sans like it were deadly poison. He felt that shrieking pain in his soul, but he hung his head low. His anger and sorrow were surfacing, and he doesn't know if he could contain in himself any longer. 

"Don't just stand there!" Papyrus jutted his foot into Sans's ribs, "Move and fix them!"

Sans cried out, whimpering as tears started to form in his eye sockets. He forced them not to fall off.

“y-you d-don’t understand”, He whined, weakly propping himself up from the floor as he held his damaged ribs where Papyrus hit them.

“What?” Papyrus leaned in to catch what Sans was saying. He had no time for this.

“ _you don’t understand_!” The short skeleton swatted his hand against Papyrus, his left eye burning bright red while the right was pure black.

“Sans”, Papyrus suddenly felt the danger within his smaller brother. He took a step back, but if he doesn’t act now to calm his Sans, it might create more havoc.

“you don’t understand you don’t **_understand you don’t understand_**!” Sans held his head with his hands, his glowing red tears were pouring down profusely. He can’t stop them now.

Fuck. He need to make a move now. Papyrus growled, crouching low as he cautiously approach his brother, his aura resonating, calling out to Sans’s. He could hear the other howling in agony.

“ ** _get away from me_**!” Sans roared, falling onto his knees. Two red flashes appeared behind him, taking form of the most famous things.

Gaster Blasters.

Papyrus started to panic. If he could not calm Sans, he would be dead on the spot for being targeted directly by the Gaster Blasters. He had to do something he never done before, seeming that this was the only way end this.

Connect their souls.

“Sans!” Papyrus gritted his teeth as his own aura burst out with more life around him, overwhelming and towering over the shorter skeleton. The Gaster Blasters growled and opened their mouth, ready to charge up their lazers at the sensing threat. Papyrus boosted his determination to push through and darted off towards Sans quickly, sliding onto his knees and captured his brother in his arms, hugging him tight and forcefully connect their souls unwillingly.

Sans cried out at the sudden contact, the sudden loss of his power dropped dramatically, causing his Gaster Blaster to disappear in a wink. He wanted to push away his brother. He did not deserve this at all. He was nothing but a worthless scum. However, Papyrus held on, embracing him even tighter. Their souls beat rapidly against each other, the older sending soothing lullabies to the young one. The vast of emotions mixed themselves to each other. Sans felt the coldness and the pride that his brother lived in, while Papyrus felt the frustration and desire for love and affection from him.

 

Sans whimpered, feeling a sudden weakness taken a hold of him. His aura faded, but Papyrus burn bright for a few more seconds before he too faded. They both panted on the floor, the depressed skeleton slumped on the boastful one. Papyrus did not say anything. He was speechless from the recent secret he just uncovered from his brother.

“I’m s-so sorry”, Sans apologized, choking on his sobs, “I’m so weak… I can’t be strong like you.”

Again, Papyrus stayed silent. He was about to reassure his brother by hugging him tight, but instead he stood up and walked away.

“Go to your bedroom and rest. You are excused from work,” Papyrus whispered in such a rare gentle tone. He then proceed to walk out of the scene quietly.

Sans watched him leave. Even after experiencing the pain he had endured, his brother still did not care. He felt numb from the emotional outburst, so he stood up and limped his way back into his bedroom.


	2. Chapter 2

The next day, Sans had not been seeing Papyrus any more often. He only catch glimpses of him associating orders with the servants and him going back into his throne room to continue his business. Unfortunately, Sans dare not to enter the throne room anymore. The ‘accident’ they had yesterday, was totally not a pleasant one.

As time continued, Sans felt even more depressed. Now not only did he not get the desire he waited for eternity, but also not being able to interact with his brother much. Talking to him was nice sometimes, especially the rare occasions when Papyrus decided to have a small talk about how things were going well.

He could not think straight anymore, and the constant thoughts of suicidal haunted him even more. Sans’s only reason to live was Papyrus, but if life decided to take his brother whom he admired, he might as well jump off a cliff.

Sans walked past monsters who hurried off to their working place. He watched them run, hearing their shoes noisily tapping on the ground as they do. Sweat beads formed on Sans’s forehead. Wait… Should he be going to work? Sans began to be anxious, sweating even more nervously. He should. Then maybe he would earn a reward from this. He just got to be patient.

~~~~

Sans skipped his way so fast that he couldn’t believe himself. He was never this determined before. So he made sure he would put this into a good use. Sans ran towards where he recently destroyed the building yesterday. He forced a smile when the constructor workers whipped their heads in awareness of his presence. They all didn’t have a good feeling about this.

“hey, relax”, Sans smirked, waving his hand in reassurance, “thought I should help you guys out. I’m really sorry for the destruction I caused.”

He approached them in a calming manner, showing that he didn’t mean any more foolishness. He noticed a worker having trouble carrying the boxes, so he snapped his fingers and red aura clouded around the box, levitating them to where the worker was supposed to place it.

“U-uhm, s-sir”, the leader stammered, taking a step forward towards the short skeleton.

“mhhm?” Sans turned to look at the leader.

“S-sorry to bother b-but”, the leader bowed his head, “Lord Papyrus told m-me that y-you were excused from any kind of work. H-he announced it to all of us, saying that y-you should rest.”

Rest? Excused from any kind of work? When did this happened? Sans was confused, but he did not show it on his expression. Instead he revealed that he understood.

“oh… uhm”, His face darkened, “is that so? Heh, heh. Alright, I’ll leave.”

Sans abandoned his goal, his determination shrunk. Was this all some sort of punishment? But if Papyrus said that he was excused just so he could rest, surely it was an act of compassion? He had a strong feeling that was not the exact reason.

A side of him told him that he should shrugged it off and do what his Papyrus wants. The other bugging him to confront his brother and get the reason out of him. He was in a dilemma, and this wasn’t helping to reduce his anxiety. After struggling with his thoughts, he made haste towards the throne room.

~~~~~

Papyrus was sitting on his usual chair. His face leaning against his propped up hand on the arm rest, while his other tapped in a bored manner. He stared out of the window of his capital that viewed the most of the city. He let out a sigh. He wasn’t in the mood for the work today. Stress got the better of him for the first time ever since yesterday after his discovery of his little brother’s secret. He was so devastated, if that was the correct term to describe it, to realize how his brother was this desperate and clingy.

Had he been a really bad brother?

Papyrus let out a distressed sigh again. He leaned back against the chair, closing his eye sockets to take a break. He needed some peace.

Unfortunately, that peace did not last long when there was a knock on the throne door.

“Come in”, he groaned annoyingly.

He heard the door creaked open and closed behind the person. Then heavy steps were sounded as the person made his way to the Lord.

“hey there brother”, the familiar voice made him flinched a bit, causing him to twist his head to face Sans.

“What are you doing here?” Papyrus hissed.

“oh, nothing much”, Sans chuckled as he took out his handkerchief to wipe away his sweat that had formed on his skull, “just wanted to visit you and ask,

“ **why do you have to forbid me from doing work**?”

“I am certain you got your answer from whoever you tried working with.”

“well I am more certain that _‘I need rest’_ was not the main reason.”

“What reason do you want to hear, Sans? I do not have time to play with your games,” Papyrus snapped, clearly irritated by this.

Sans frowned and gritted his teeth, his fists tightened in his coat pockets.

“I don’t want the reason. I want the truth”, Sans hung his head low, struggling to keep his emotions in check, “you really hate me, don’t you? I can fucking leave if you want me to. I’ll even kill myself if I have to. Just say it and _I’ll do it._ ”

Papyrus stared at him. He was at a loss of words.

“you know what? I’m leaving right now. I just came here to say goodbye”, Sans wiped away the escaped tears from his cheeks. He turned around to leave when Papyrus reached out to tug back his hoodie.

“wha-?” The next thing he knew, he was hauled from his feet, making him yelp in protest. Oh shit, did he offended his big brother? _Fuck fuck fuc-_

Sans trashed around, trying to make Papyrus lose grip on him. Tears were forcing their way out of his eye sockets once more.

“Calm down”, Papyrus growled, wrapping his arms around Sans’s middle, gripping him tight. Both of them wrestled on the throne chair. Sans, due to his stubbornness, did not listen. He screamed and struggled, kicking his legs in the air.

The big brother snarled, his aura coming to life around the both of them. His soul reached out to Sans, forcing and urging him to connect his soul with him. Sans refused, pleading him to let him go, “n-no! stop!”

“Don’t resist it”, Papyrus whispered to him, his chin buried into Sans’s neck, “I know you wanted this for so long. I felt it.” His grip tightened, his soul forming a magic connection with the other, like what they did yesterday.

Sans sobbed, his struggling reduced. He soon laid still against his brother’s chest, crying weakly.

“p-please”, Sans begged, shaking his head, “I don’t deserve this. I’m nothing but trouble to you.”

“Shhh”, Papyrus hushed him, planting soft kisses on his little brother’s cheekbone. His hand sliding onto Sans’s chest to caress it soothingly, nudging his soul to complete the connection.

Sans whimpered. He knew there was no backing out now. And if he did, maybe this would never happen again. He willingly submitted, letting his soul fly close to his big brother’s and fill in the connection between them. The magic connection sparked between the both of them, sending short bolts of pleasure to duo. Sans let out a shaky moan, jerking slightly on Papyrus’s lap.

After a few seconds, Sans slumped completely, feeling the mixture of emotions he was receiving from the bond with his big brother.

“P-papyrus”, he buried his head under his neck. He was battling himself not to cry again.

“Sans”, Papyrus nuzzled his fore head, his hand now sliding onto his little brother’s belly, rubbing it, “It’s okay… Let it out.”

And let it out he did. Sans poured out all of his dispirited feelings, rippling through the bond. His sobbing became louder, and Papyrus eagerly delivered his consoles to comfort his broken brother. His belly rubbing seemed to have relieved the both of them. Sans, for reassurance, while Papyrus, stress-relieving.

Papyrus hummed. And soon, Sans became calm, though apparently, he had fallen into a deep slumber, obviously exhausted from his emotional outburst once again. Papyrus snickered. He found the short skeleton’s soft expression very adorable. He warmly smiled and gave another kiss on his brother’s forehead, before hugging him and continued to stare through the window of his capital, enjoying the scenery of the city more than ever before.


	3. omg its here now

**Notes for the Chapter:**

> THIS CHAPTER CONTAINS SEXUAL SCENES. IF YOU DONT LIKE INCEST/FONTCEST, HOLD YOUR HORSES AND GO BACK TO WHERE YOU COME FROM.

Days got even more awkward after that. They still interact with each other, but they both knew whatever they felt towards each other, whenever they were together, it would not be the same as before. Papyrus got even more busy, and Sans did his job properly every now and then. However, the time spent between the two of them, it was not enough for Sans. Surely his anxiety decreased, but his craving for love was not satisfied yet.

He whined at the thought of this, but he told himself he should be grateful that his relationship between his brother was stabilized. He would often give himself logical reasons to lessen his heartaches.

It was time for bed. Sans sighed and dragged his feet when he made his way to his bedroom. He doesn’t like sleeping alone, unfortunately he had to bear this with the rest of his life. Sans yawned as he took a shortcut to his bedroom, collapsing onto his bed as he entered a deep slumber, only to be greeted by a waiting nightmare.

~~~~

Papyrus slid his hand down his face, completely exhausted from his work. Today totally sapped out his energy, and he deserved a good night rest. He walked down the hallway that leads to his bedroom, until he walked past Sans’s bedroom. He paused, staring intently at the door.

There were times Sans knocked on his door, crying that he got a really bad nightmare. He asked whether he could sleep with Papyrus for the night, but the hot headed brother wouldn’t let him. Papyrus would just tell him to ‘face his fears’ or ‘get used to it’ before shutting the doors shut harshly and went back to sleep.

Papyrus knew that Sans did try to face his nightmares only to be ended up being futile. He had seen him slouched while doing work, visibly tired and deprived of sleep. The big brother did not had any concern on this issue, because it wasn’t his ‘problem’.

But after what had happened the past few weeks, he stood there before his little brother’s bedroom, considering whether he should enter and sleep with him, or to just get back to his own room. He had never been inside Sans’s room, not even once. He clenched his fists and let out a sigh, before turning the door knob and gently pushed the door open silently.

The view was not a pleasant one. There were socks scattered everywhere on the floor, and a pile of smelly clothes were dumped in one corner. The desk was full of crushed up papers, and broken pencils. Papyrus gasped in disbelief. He knew that this was a sign of depression when one’s room was messy and disorganized. He turned his head slowly over the bed, where his Sans was sleeping. Except that he wasn’t sleeping peacefully. He was murmuring “no”, “stop”, and “I’m sorry” all over again. Those familiar tears rolled down his cheeks again, faintly glowing in the dark. He brawled in his sleep.

Papyrus entered the chaotic room and closed the door behind him, scurrying over to his despondent brother who was having a nightmare. He slid himself under the sheets of the bed, shaking violently to wake up his brother.

“Sans,” He called out to him, “Wake up, it’s just a bad dream!”

However, the little brother did not. His aura were lit around him, and it seemed that it was getting stronger and could scorch the whole room any time now. Sans screamed in his sleep, his hands clutching his head, curling into a tight ball.

 _Shit_ , Papyrus cursed mentally. This had never happened before. And the only way to bring his brother back to reality was the magical connection method. He growled to himself as he brought his own aura to life, his soul automatically dashing forward to retrieve the lost soul of the other. Surprisingly, there were no resistance this time. Sans’s soul desperately clung onto the magical connection, making contact with Papyrus’s soul and released a huge bolt of pleasure through the both of them, making the unexpected Papyrus to throw his head back and let out a moan unintentionally. He glanced down on Sans, and called out to him once more.

“Wake up!”

Sans snapped open his eye sockets, his left eye burned in furious red flames. He yelled and latched onto Papyrus, his hands closed tightly around his scarf. Sweat were dripping down his forehead non-stop, his breathing was loud and heavy.

“Hey, hey”, Papyrus cooed, bringing his hand up to slide his thumb soothingly on the Sans’s forehead, “It’s me, Papyrus.”

“B-brother?” Sans had to process this familiar presence before him. He was still haunted by the nightmare he had just experienced.

“i-i, i-I’m s-so s-sorry”, Sans gripped tightly onto Papyrus’s scarf, burying his face onto it. He broke down, his wet tears staining it, “p-please don’t hurt me!”

So Sans dreamt about Papyrus abusing him.

“I won’t hurt you”, Papyrus comforted him, pulling back slightly so that he could press his forehead against his brother’s, “I promise it would never happen again.”

Sans continued to hiccup in his sobbing. His hands were around his tall brother’s neck. He doesn’t want to let him go.

“I’m sorry if I never knew that you felt this way,” Papyrus tilted his head to one side, his teeth touching the other’s to resemble a kiss, “after all of these years… I beg for your forgiveness of causing much sorrow in your life, Sans”.

Red color flustered themselves on Sans’s cheekbones. It was his aura doing. He started to feel embarrassed and weak, trying to push himself away from all of this desire he craved because it felt wrong to do this to his brother.

“Don’t resist it”, Papyrus smirked, his mouth opening to reveal a wet, red-orange tongue, giving a long slick lick on his brother’s cheek, “You can’t hide anything from me now”.

“P-papyrus”, Sans mewled. His body started to heat up and his soul started to resonate through the arousal. Papyrus’s soul joined in the hunger, expressing his aggressive lust in the shared bond. His aura was dominating him, and so his soul became weak and submissive.

“Just lay still”, Papyrus attacked Sans’s neck with bites, kisses and licks, “and let me do all of the work”.

Sans jerked his hips up, letting out a strangled moan. He was about to shove his brother away and tell him to slow down but magic tentacles erupted from Papyus’s soul and chained his hands together above his head.

“W-wait- a-aah!” Sans pleading was cut off when Papyrus opened his jacket and caressed the sensitive ribs.

“Nyeh heh”, Papyrus chuckled, “looks like I wasn’t wrong of you being sensitive bones.”

Was that meant to be a pun? It doesn’t matter, because he doesn’t have the time to think properly when pleasure was overwhelming him. Sans felt an erotic sensation in his shorts, and he immediately knew it was his dick being formed. It wasn’t his will. Once a skeleton gets aroused, their aura automatically builds their magical ‘sexual organs’.

Papyrus grabbed Sans’s shorts and yanked them out from his legs without any warning. The cold air brushed against his heating area, earning another moan from the short skeleton.

“Desperate, aren’t you”, Papyrus teased, his hand wrapped around the member, which was already dripping pre-cum. Sans shivered at the touch, avoiding eye contact with Papyrus. The prideful brother applied pressure, causing the other to hitch his breath.

Papyrus leaned forward, his glowing tongue slid out and licked up the pre-cum that was oozing out from the urethra. Sans cursed through his breath, his back arched at the sudden jolt of pleasure. Papyrus wasted no time as he took his little brother’s member into his mouth and began to suck it.

“ _F-fuck_!” Sans gasped out. His body was jerking due to the mind-boggling bliss he was feeling. Damn, his brother sure does know how to do this. There was no doubt that he too wanted this for a long time.

Papyrus rubbed at the base of the dick while the rest he sucked harder. Soon, his pace quickened, bobbing his head up and down and furiously rubbing at the base. In less than 10 seconds, Sans felt that short jolt of pleasure and came, his cum shooting itself into his big brother’s mouth.

He slumped onto the bed, already exhausted from his first orgasm.

“I’m not done with you”, Papyrus growled huskily, his hands sliding under Sans’s thigh bones and lift them up, their hips pressing close. Sans’s froze when he felt something nudging against his tailbone, which had a barrier of an asshole visible.

“h-hey, c-can’t you give me a brea-?!” Sans clamped his mouth shut when Papyrus shoved his hips forward, his massive formed dick penetrating itself into his ass.

“Hhhgnn”, Papyrus tightened his hold on Sans’s thigh bones while he buried his head on Sans’s neck, his warm breath making the other even more hotter than he already was, “Gosh… Sans, _you’re so tight_!”

“a-and you’re t-too big”, Sans winced, panting as he felt his has being violated by the huge dick of his brother.

Papyrus moaned, so eager to have his orgasm right here and right now. He bit down onto Sans’s neck as he pulled back his hips and thrust in again, evoking more groans from the smaller skeleton.

“You wanted me like this”, Papyrus mocked him, his pace not going any slower, “ ** _dominating with full control of you_**.”

Sans couldn’t say anything. His mind was in a daze, all of his focus were on him being fucked senseless. Papyrus snickered as he slammed his hips forward soundly, rapidly increasing his speed of thrusting his dick into Sans’s ass. He eventually let go of the tentacles that were holding down his hands, allowing Sans to wrap his arms around his neck to get a hold of himself.

Sans moaned, finding himself to desperately grind his hips down to meet the thrusts of his brother. He wanted deeper, faster. He felt his second orgasm coming and he needed it so badly.

Papyrus gnarled, his soul in the magical connection snatched Sans’s soul in a tight ‘embrace’, small aura strings coiled itself around the heart to educe more pleasure for the both of them. He used his remaining strength and thrusted his hips hard and sloppy, catching up on his orgasm with Sans until they both came as pleasure overwhelmed them.

They both let out their satisfied cries before Papyrus slumped on the bed with Sans’s on top of him. His member was still inside of him, though he had no intention of pulling it out. It would probably fade away once they wake up the next morning. Their powers were still crazed and tangled, souls still connected with Papyrus’s still clinging onto Sans’s. It would take the whole night for their powers to go back respectively to the rightful owners.

Sans nuzzled Papyrus’s cheekbone, mumbling, “ _I love you_ ”, before he eventually passed out from his sex exhaustion.

Papyrus chuckled, admiring the facial expression of his brother before pecking a kiss and closed his eye sockets, saying, “ _I love you too_ ”, and entered a peaceful sleep with his Sans.

**Notes for the Chapter:**

> FINAL CHAPTER YES. WHOOOOOOOOOOAAAA THIS STORY WAS A BUMPY RIDE!!! HOPE YOU GUYS ENJOYED IT

**Author's Note:**

> hohohoh please leave kudos and comments if you enjoyed it!


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